纳米层状双金属氢氧化物改性PU/PMMA的制备及其弛豫行为  

PREPARATION AND RELAXATION BEHAVIOR OF LAYERED DOUBLE HYDROXIDE MODIFIED PU/PMMA NANOCOMPOSITES

作　　者：余雯雯[1] 傅华康[1] 张德志[2] 杜淼[1,3] 郑强[1,3] 

机构地区：[1]浙江大学高分子科学与工程学系,杭州310027 [2]中国船舶重工集团公司第七一五研究所,杭州310012 [3]浙江大学高分子合成与功能构造教育部重点实验室,杭州310027

出　　处：《高分子学报》2013年第9期1212-1218,共7页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号51173157);中央高校基本科研业务费专项基金(基金号2011QNA4025)资助

摘　　要：采用原位聚合法,制备了聚氨酯(PU)/聚甲基丙烯酸甲酯(PMMA)/层状双金属氢氧化物(LDH)纳米复合体系(PU/PMMA/LDH).通过广角X射线衍射(WXRD)、透射电子显微镜(TEM)对其结构和形貌进行了表征,并通过热失重(TGA)、动态力学分析(DMA)和宽频介电谱(BDRS)研究了LDH含量(φ)对PU/PMMA体系热稳定性和弛豫行为的影响.结果表明,当φ<1 wt%时,LDH在聚合物基体中以剥离结构为主,PU/PMMA/LDH体系的玻璃化温度(Tg)降低,最大损耗因子(tanδmax)增大;而当φ>1 wt%时,LDH在聚合物基体中以插层结构为主,插层结构对聚合物分子链的限制使复合体系的Tg升高、tanδmax降低.LDH表面与PU硬段间的氢键作用,使复合体系的α介电弛豫转变随φ增加而向高温方向移动,弛豫过程激活参数增大.Polyurethane /poly（methyl methacrylate） /layered double hydroxide（PU /PMMA /LDH） nanocomposites were prepared by means of in situ polymerization with different amounts of the organo-modied LDH.The structure and morphology of nanoparticles were characterized through wide-angle X-ray diffraction（WXRD） and transmission electron microscopy（TEM）.The effect of the content of LDH（φ） on the thermal stability and relaxation behavior for PU / PMMA / LDH composites were investigated by using thermogravimetry analysis（TGA）,dynamic mechanical analysis（DMA） and broadband dielectric relaxation spectroscopy（BDRS）.The results of TGA testing indicated that excellent thermal stability properties of PU/PMMA/LDH nanocomposites could be achieved when the LDH loading（φ） was 0.5 wt%.An exfoliated dispersion of LDH layers in PU / PMMA matrix was varied through the WXRD and TEM observations when φ was less than 1.0 wt%.Based on the DMA results,it can be found that the maximum of loss factor（tanδ max） of PU/PMMA/LDH nanocomposites increased and the glass temperature（T g） decreased with the increase of φ.However,when φ was larger than 1.0 wt%,intercalated LDH layers reduced molecular mobility of polymer matrix and resulted in lower tanδ max value and higher T g than those of pure polymer.Moreover,it has been found by means of BDRS testing that all of α relaxation processes for nanocomposites shift to higher temperatures and the relaxation parameter increases with the increase of the LDH loading due to the formation of hydrogen bonding between the surface of LDH and the hard segment of polyurethane.

关 键 词：聚氨酯 聚甲基丙烯酸甲酯 纳米LDH 形态 弛豫 

分 类 号：O631.3[理学—高分子化学] TB383.1[理学—化学]